<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
  <h1>BMI指数</h1>
<form action="bmi">
    身高:<input type="text" name="height"><br>
    体重:<input type="text" name="weight"><br>
    <input type="submit">
</form>
</body>
</html>